The present invention is directed to freely pourable, homogeneous, water-based shampoos with enhanced stability and foam quality. More particularly, the invention is directed to shampoos containing detergents, hair grooming agents and saccharides.
The minimum function of a shampoo is to cleanse the hair. Cleansing is accomplished by removing natural oils, which are called sebum, and extraneous substances which accumulate from the atmosphere or are added intentionally, e.g., hair spray resins.
In order to cleanse the hair, shampoos generally contain a cleansing agent such as a detergent or soap. Detergents are preferable to soaps because of a detergent's ability to provide rich lather during use regardless of water hardness. A rich lather is advantageous because it enhances consumer perception of the shampoo and adds to its commercial acceptability.
It is also desirable for a shampoo to leave the hair in an improved condition for combing, to make the hair more manageable, to provide greater body and luster, to prevent fly-away, to minimize static electricity in the hair, to improve the tactile impression of the hair, and the like. These and other similar effects come under the general heading of hair conditioning.
In order to provide hair conditioning in addition to cleansing, a hair conditioning or grooming agent is advantageously added to shampoos. In order to function properly, the hair grooming agent must become deposited on the hair during the shampooing operation. In addition, it must remain deposited after the rest of the shampoo composition has been removed by rinsing the hair with water. It is the presence on the hair of the deposited hair grooming agent that provides the conditioning.
Consumers generally desire shampoos which are sold in the form of pourable, homogeneous liquids. Such shampoos are preferable to other forms because they are easier to dispense homogeneously onto the hair. Dispensing the shampoo homogeneously is especially important with those shampoos which contain hair grooming agents. If such shampoos are not dispensed homogeneously, the hair grooming agent will be unevenly applied to the hair and the hair will take on an uneven appearance.
One way to assure good deposition of the hair grooming agent from a freely pourable shampoo composition is to use a material which is homogeneously dispersed in the composition but which separates from the other ingredients when the composition is diluted with water during the shampooing process. For example, co-assigned U.S. Pat. No. 3,932,610 is directed to shampoo compositions which contain hair grooming agents made substantially soluble in an aqueous-based shampoo composition by properly selecting the solvent and/or solvent-surfactant system. Such hair grooming agents are generally insoluble in the amounts of water normally used in the shampooing and rinsing operations.
Homogeneous shampoos need not necessarily be actual solutions. Hair grooming agents or other ingredients may also be present in the form of colloidal dispersions or emulsions. If particles dispersed in a shampoo are too large to be considered colloidal, the shampoo may be in the form of a suspension of particles homogeneously dispersed in a liquid. Suspensions are normally not stable, however, unless the liquid is sufficiently viscous.
Unless all of the ingredients are soluble or otherwise homogeneously dispersed in water, co-solvents must be added in order to assure a homogeneous shampoo. Alcohols are frequently added as co-solvents in shampoos. Shampoos containing alcohol co-solvents are described in co-assigned U.S. Pat. No. 3,932,610. The alcohol may be monohydric such as ethyl alcohol, dihydric such as dipropylene glycol, or trihydric such as glycerine. Some of these alcohols, especially the monohydric alcohols, are disadvantageous because they irritate the skin, suppress foam and reduce viscosity. The dihydric and trihydric alcohols are disadvantageous mainly because of their high price. Glycerine may enhance foam somewhat but is extremely expensive.
It is also known to use saccharides in shampoos. Patents disclosing the use of saccharides in shampoos include U.S. Pat. Nos. 3,998,761, 3,988,438 and 2,237,629.
In order for deposition to occur, some attraction between the hair grooming agent and the hair must exist. The hair is negatively charged. Thus, effective hair grooming agents must be able to deposit on negatively charged surfaces.
Cationic grooming agents deposit on hair readily since they are strongly attracted to hair by the opposite charge. Since useful cationic grooming agents tend to have relatively high water-solubilities, most are soluble in water-based shampoo compositions.
Cationic hair grooming agents are typically cationic polymers and resins, such as cationic starch or cellulose derivatives. Some examples of cationic hair grooming agents are described in the following U.S. Patents:
U.S. Pat. No. 4,048,301 PA1 U.S. Pat. No. 4,009,256 PA1 U.S. Pat. No. 3,992,336 PA1 U.S. Pat. No. 3,990,991 PA1 U.S. Pat. No. 3,958,581 PA1 (a) about 15 to about 70% by weight of a water-miscible saccharide; PA1 (b) about 20 to about 75% by weight water; PA1 (c) about 0.1 to about 30% by weight of at least one nonionic or cationic hair grooming agent; and PA1 (d) about 3 to about 60% by weight of an anionic detergent, PA1 b is an integer having a value of from 2 to 3; PA1 c is an integer having a value of from 1 to 3; PA1 m is an integer having a value of from zero to 10; PA1 n is an integer having a value of from zero to 3; PA1 p is an integer having a value of from zero to 10; PA1 q is an integer having a value of from zero to 1; PA1 R' is a member selected from the group consisting of ##STR2## with the proviso that when q is zero then R' is --H; and V is the valence of X PA1 R.sub.1, R.sub.2 and R.sub.3, taken individually, represent a member selected from the group consisting of alkyl, aryl, aralkyl, alkaryl, cycloalkyl, alkoxyalkyl and alkoxyaryl radicals where each of R.sub.1, R.sub.2 and R.sub.3 can contain up to 10 carbon atoms, with the proviso that when said member is an alkoxyalkyl radical there are at least 2 carbon atoms separating the oxygen atom from the nitrogen atom, and with the further proviso that the total number of carbon atoms in radicals represented R.sub.1, R.sub.2 and R.sub.3 is from 3 to 12; PA1 R.sub.1, R.sub.2 and R.sub.3, taken together, represent, along with the nitrogen atom to which they are attached, a member selected from the group consisting of pyridine, -methylpyridine, 3,5-dimethylpyridine, 2,4,6-trimethylpyridine, N-methyl piperidine, N-ethyl piperidine, N-methyl morpholine and N-ethyl morpholine; PA1 X is an anion such as chloride, bromide, iodide, sulfate, methylsulfate, sulfonate, nitrate, phosphate, acetate, etc., and V is an integer which is equal to the valence of X; PA1 R.sup.1 and R.sup.2 are each dependently PA1 M is a water-solubilizing cation, PA1 A is PA1 B is
The hair grooming agent may also be a nonionic material. Various water-insoluble resinous, oily and waxy materials such as wood rosin, mineral oils and cocoamide constitute suitable nonionic hair grooming agents. These and other nonionic hair grooming agents are described in co-assigned U.S. Pat. Nos. 3,932,610, 3,950,510 and 3,533,955.
Nonionic hair grooming agents that have received considerable attention recently are the silicones. An article by Todd et al in "American Perfumer and Cosmetics", 86, 112 (1971) refers to the silky feel which silicones impart to hair. Silicones are also disclosed as hair grooming agents in shampoos in U.S. Pat. Nos. 4,087,518, 3,964,500, 3,950,510 and 2,826,551.
It is also known to increase the water-solubility of silicones. This may be done, for example, by providing a copolymer containing silicone and an alkylene glycol. Shampoos containing such solubilized silicones are described in U.S. Pat. Nos. 3,957,970 and 3,533,955.
It is frequently advantageous to provide a shampoo comprising both nonionic and cationic hair grooming agents. Such shampoos realize the separate benefits of both types of conditioners. Moreover, each charge type may actually enhance the benefits of the other.
Hair grooming agents may also be of the anionic type. In addition to containing the saccharide sorbitol, U.S. Pat. No. 3,988,438 (see above) describes a shampoo containing an alginate salt as a hair grooming agent. Anionic hair grooming agents, however, deposit on negatively charged surfaces such as hair with difficulty due to electrostatic repulsion. Thus, most hair grooming agents are nonionic, cationic or mixtures thereof.
That is not to say that literature reports have not shown substantially of anionic hair grooming agents, and even detergents, to hair. Anionic grooming agents, however, deposit much less liberally from detergent systems than do cationic or nonionic agents and do not give the magnitude of effect of cationic or nonionic agents under comparable conditions.
Not all shampoos are freely pourable and homogeneous. Non-pourable, concentrated forms of shampoos such as gels and creme pastes have been known and used for some time. Such shampoos are added to only part of the hair and are worked into the rest of the hair after being diluted with water. Concentrated shampoos are unsatisfactory since homogeneous dispersion of the hair grooming agent throughout the hair is difficult. This incomplete dispersion leads to a disadvantageously uneven distribution of the hair grooming agent on the hair.
Two-phase shampoo systems have also been described; see, for example, U.S. Pat. No. 3,533,955. Typically, such shampoos contain a hair grooming agent in an oil phase and a detergent in an aqueous phase. Two-phase shampoos are applied to the hair in the form of temporary oil-in-water emulsions which must be formed by vigorously shaking the shampoo before use. These systems are disadvantageous because they are inherently non-homogeneous and, in addition, tend to have viscosities which are less than those preferred by consumers. Moreover, the use of two phase shampoos is inconvenient because of the requirement that they be shaken vigorously.
Despite considerable effort to improve shampoo systems, numerous problems still remain. One problem is providing a shampoo with copious form. Hair grooming agents such as silicone and co-solvents such as alcohol depress foam. Such foam suppression is disadvantageous since consumers prefer shampoos having good foam quality, i.e., having a high foam viscosity and volume.
The foaming of shampoos is caused by the presence of detergents. Thus, foam suppression due to the presence of certain hair grooming agents and co-solvents can be obviated by increasing the concentration of the detergent. Some detergents, however, can irritate the skin and the presence of high concentrations of detergents decreases the mildness of the shampoo.
Moreover, detergents lower the surface tension of extraneous materials on the hair, thereby promoting removal rather than deposition of hair grooming agents. Thus, high concentrations of detergents lower the amount of hair grooming agent deposited on the hair. As a result, increasing the concentration of the detergent enhances foam at the expense of mildness and conditioning.
Another problem, inherent in water-based homogeneous shampoos containing hair grooming agents, is that of obtaining the correct balance of stability. In the present context, stability refers to the maintenance of homogeneity. If a shampoo is too stable, the hair grooming agent will not readily deposit on the hair during the washing and rinsing processes. On the other hand, shampoos which are insufficiently stable will not remain homogeneous during storage.
Stability is a particularly serious problem in shampoos containing both a cationic hair grooming agent and an anionic detergent. This problem is discussed in U.S. Pat. No. 3,549,542. Apparently, a complex containing the cationic and anionic materials forms and settles out of the shampoo solution, dispersion, emulsion, or suspension. The instability of such shampoos can be countered by adding certain ampholytic and polar nonionic detergents and thickening agents. Special mixing techniques are also said to be helpful. Nevertheless, such methods add to the cost of manufacturing the shampoo and are otherwise not completely satisfactory.
Even shampoos which do not contain both an anionic detergent and cationic hair grooming agent are often unstable with time. The classical method for stabilizing such shampoos is by the addition of thickening agents. Thickening agents are, however, expensive and at the levels required to stabilize shampoos often decrease the pourability of the shampoo. This loss of pourability can make the removal of the shampoo from its container difficult and inconvenient. In addition, some of the shampoo may be lost since a large residue of the thickened shampoo tends to form on the walls of the container after the user has emptied the container as far as is practical.
The need continues to exist, therefore, for a homogeneous, freely pourable, stable, high foaming and mild shampoo containing effective cationic and/or nonionic hair grooming agents and an anionic detergent.